Multilayer composite articles are sometimes used to absorb sound and thereby reduce noise levels in nearby spaces. For example, sound absorptive multilayer composites may be employed in headliners, trunk liners, hood liners, dash mats, interior panels, carpeting and other porous decorative or functional vehicular facing materials to provide enhanced noise reduction in a vehicle interior.
References relating to acoustic insulation, vehicular facings or noise reduction include U.S. Pat. Nos. 5,459,291, 5,536,556, 5,549,776, 5,565,259, 5,824,973, 6,145,617, 6,150,287, 6,214,456 B1, 6,217,691 B1, 6,238,507 B1, 6,270,608 B1, 6,296,075 B1, 6,345,688 B1, 6,454,088 B1, 6,575,527 B1, 6,576,577 B1, 6,616,789 B2, 6,631,785 B2 and 6,659,223 B2; U.S. Published Patent Application Nos. US 2001/0036788 A1, US 2003/10479 A1 and US 2004/037995 A1; Canadian Published Application No. 2,350,477 A1; PCT Published Application Nos. WO 99/44817 A1 and WO 01/64991 A2; M. Schwartz and E. J. Gohmann, Jr., “Influence of Surface Coatings on Impedance and Absorption of Urethane Foams, J. Acoust. Soc. Am., 34 (4): 502-513 (April, 1962); M. Schwartz and W. L. Buehner, “Effects of Light Coatings on Impedance and Absorption of Open-Celled Foams, J. Acoust. Soc. Am., 35 (10): 1507-1510 (October, 1963); and “Guide to AZDEL SuperLite”, publication of AZDEL, Inc. available on the Internet at http://www.azdel.com/documents/Guide%20to%20AZDEL%20SuperLite.pdf.